Paramyosin binding proteins are thought to be important in the creation and maintenance of the core structure of the thick filaments of muscle in C. elegans. We would like to determine the components and ultrastructure of the core in this research. Dissociation of paramyosin from native thick filaments shows two different populations of paramyosin depending on salt concentration, one of which remains with a core structure which shows 72.5nm periodicity when negatively stained. Core particles contain proteins with masses of 20, 28, 30, 31, and 100kDa in addition to paramyosin. We have purified and sequenced peptides from endoproteinase-digested 28, 30 and 31 kDa proteins from the core particles and have used this information to locate genes coding for these proteins from the c. elegans Genome Project database. From genetic evidence, we also believe that the 100kDa protein may be a protein already sequenced and corresponding to the unc-45 locus. The 28 kDa protein does not have any matches or nearby loci to connect it with, but the 30kDa protein may correspond to the unc-82 locus. Peptide or whole protein antibodies will be made against these proteins and immunocytochemistry will determine the location of the proteins in the cells. We will attempt to find mutations that can be complemented with these genes or create new mutants using transposon tagging. Future experiments will eventually involve the reconstitution of the thick filament utilizing these proteins and the isolation of human homologs. As this work addresses basic aspects of muscle function and structure, it may be relevant to a number of muscle diseases.